Isolation and Molecular Characterization of a Putative Ascorbate Peroxidase Gene from Citrus

Abstract

Ascorbate peroxidase is the key enzyme in detoxifying hydrogen peroxide (H 2 O 2 ) and other reactive oxygen species from chloroplast and cytosol. A cDNA encoding a putative citrus ascorbate peroxidase, APXcit was isolated from mature 'Dancy' tangerine (Citrus reticulata Blanco) juice vesicles using differential display reverse transcription-polymerase chain reaction. The full-length APXcit sequence was composed of 1,082 bp nucleotides, including an open reading frame of 753 bp, putatively encoding a protein of 250 amino acids with a predicted molecular mass of 27 kDa. The 5¢ untranslated region consisted of 90 nucleotides and the 3¢ untranslated region of 239. The genomic clone of 2,457 bp was composed of 8 introns and 9 exons. A homology search for APXcit at the GenBank database showed high similarity to ascorbate peroxidase from several plant species. Southern analysis revealed that there may be 2-4 APXcit gene copies in citrus.

Cloning and characterization of an ascorbate peroxidase gene regulated by ethylene and abscisic acid during banana fruit ripening

“…The genes encoding members of the ascorbate peroxidase enzyme family have been characterized in a number of plants, including pea (Mittler and Zilinskas, 1992), bell pepper (Schantz et al, 1995), spinach (Webb and Allen, 1995), Arabidopsis (Santos et al, 1996), maize (Bresegem et al, 1995), tobacco (Ovar and Ellis, 1997), strawberry (Kim and Chung, 1998), tomato (Gadea et al, 1999), potato (Kawakami et al, 2002), cotton (Li et al, 2007), melon (Cheng et al, 2009) and citrus (Kunta et al, 2010). In this study, we characterized the APX gene from banana; the cDNA sequence showed very high identity to other known cytosolic APX proteins, with the closest match to Z. mays (86%), Z. aethiopica (81%), G. hirsutum (78%) and V. vinifera (78%).…”